What is a smart material?

Louise Smyth

Also referred to as ‘responsive’ or ‘intelligent’ materials, smart materials have been around as long as the Pyramids of Giza. Their potential is far-reaching within the engineering industry and is only now being tapped into.

What are smart materials?

A smart material is an object that holds a property that is susceptible to change with the introduction of an external stimulus. This change must be either tangible or visible for the material to qualify for ‘smart’ status. These changes can include:

  • Electrical
  • Chemical
  • Thermal
  • Mechanical
  • Magnetic

The definition of smart materials has been expanded recently to include any materials that may not display a physical change,  but do hold electronic functionality.

Material scientists and smart materials

Common examples of products that hold intelligent materials include:

  • Mood rings
  • Responsive glasses that darken when in direct sunlight
  • Colour-changing mugs

While these may not be considered particularly groundbreaking, material scientists are continuing their studies to ascertain potential applications of other materials.

What are the different types of smart materials?

There are a wide variety of smart materials with differing functionality and applications see Figure 1

What are the problems with smart materials?

Although the applications of smart materials (both current and futuristic) are far-reaching, some drawbacks are preventing a heavier reliance on them, such as:

  • Delicacy
  • Instability
  • Diminished performance over time
  • Incorporation difficulties
  • Toxicity
  • Costs

Future applications of smart materials

Concepts surrounding the futuristic application of smart materials include:

Aerial industry

The application of smart materials will enable the wings of aircraft to be more flexible thanks to shape-memory alloys. The outer elements of an aircraft will become more skin-like in that they will have to be strong, hard and rigid, yet flexible.

The theory behind this design stems from Da Vinci’s flying machine, an example of a historic smart material theory being realised with tomorrow’s modern technology. The ‘skin’ of the plane will also have self-healing properties, even when the aircraft is in flight; thanks to the introduction of self-healing plastics.

Energy Sector

The implementation of printed photovoltaic cells will allow the energy sector to take solar panels to the next level. Photovoltaic cells can be painted onto any surface, in any shape. These cells can transform sunlight and heat into electricity. This will undoubtedly have a positive impact on residential properties and, while this solution is not yet commercially-ready, the industry is certainly getting closer.

Mobile industry

There are LG devices that already contain self-healing materials, restoring any scratches that occur on the back of the device. However, research is currently taking place to move this on to another level. The aim is to invent self-healing glass (for screens) and lithium batteries that can be housed within mobile devices.

Automotive industry

Windscreen chips become cracked due to water molecules within the air mixing with the chip in the glass, breaking it down and worsening the condition. Crack-resistant glass is currently in development that reacts well with airborne water molecules, resulting in the glass healing over time instead of deteriorating.

As material scientists continue to study intelligent materials, further future applications will be discovered. The opportunity within the energy, automotive, medical and even military sectors are sure to benefit from the technological advances available through the incorporation of smart materials.

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